Janet Kwasniak's blog on consciousness and the brain

Tag Archives: Cambrian explosion

I have just read a book by Feinberg and Mallatt, The Ancient Origins of Consciousness – How the Brain Created Experience. It may turn out to be one of those classic books that cause a big change in accepted science. They tackle the ‘mystery of consciousness’ in a new way, a very biological way. The book ends with, “a satisfying and complete explanation of primary consciousness requires a confluence of points of view, necessarily including neurobiological, evolutionary, and philosophical arguments, each contributing important answers to the ‘hard question’. Perhaps one reason no one has solved it before is that it requires all three perspectives, including what happened over half a billion years ago.” I assume there will be many who find the book’s theory wanting because of they view neurobiological naturalism is impossible and believe normal science cannot explain consciousness. The authors brand of neurobiological naturalism has three postulates which the book documents:

1. “sensory consciousness can be explained by known neurobiological principles”

2. “sensory consciousness is ancient and widespread in the animal kingdom, and diverse neural architectures can create it”

3. “the philosophical issues of ontological subjectivity, neuroontological irreducibility, and the ‘hard problem’ can be explained by the nondissociable confluence of neurobiological and adaptive neuroevolutionary events.”

The book has changed my ideas in a number of ways. First to fall was my attitude to the idea of ’emergent properties’. I have viewed it as a hedge, a cope-out, and even a way to bring dualism back in disguise. This book describes emergence in a way that makes sense. In a layered hierarchy each layer is created from the layer below but is more complex with novel elements which are labeled as emergent. But the external constraints act primarily on the top layer which constrains the layers beneath it. Thus there is both control and innovation by both bottom-up effects and top-down effects. Yes, this arrangement does need its own name and is a typical situation in living organisms. “In living systems such as the human body, cells constrain their subunits (organelles) to work together, the tissues and organs constrain their cells to cooperate, and the entire body constrains its organs to team up, all to perform the many physiological functions needed for the body to survive. If the constraints were to fail at any level, the body would disassemble and die.” A particular type of layered hierarchy, nested maps of the sensory organs such as the retina, is the basis of consciousness.

My second change of thinking was about the nature of the Cambrian explosion. It had seemed to me that the changes between geological periods were caused by changes to the environment like a meteor strikes which kill off the dominant animals and plants and allowed the others to flourish. But the book makes a case of a change to some animals being the cause and not the result of the abrupt explosion 560 – 520 million years ago. The result was new lines of animals which have populated the earth ever since. Predators appeared for the first time and this resulted in an arms race between predators and prey. There were many adaptations, and among them, improved distance sensing: vision, hearing and smell. Anthropoids and vertebrates in particular evolved high mobility and brains that improved sensory processing. A key change was image forming eyes. These allowed topographical maps of the retina. The other senses in vertebrates (except smell) re-evolved from a new cell line, on the pattern of the eye and its mapping in brain. In the resulting hierarchy of topographical maps for the senses, consciousness evolved.

I had assumed that the source of consciousness was lower in the brain than the cerebrum but was surprised by the location. The book documents it arising first in the optical tectum (superior colliculus in humans) and later extending to the thalamus and cerebrum, 220 years ago in mammals. This move not only added more layers to the existing hierarchies and put the top layer in close proximity to the sense of smell and its related memory in the cerebrum. This was a major advancement for consciousness for mammals and later for birds. Again I had to change my view as I had thought that memory and consciousness were always tightly bound.

The book also traces the evolution of affective consciousness (feelings and emotions), just as old as sensory consciousness. What was news to me was the intermingling of interoceptive bodily senses and affective limbic feelings giving three strains of consciousness.

The authors point out that the experience that the brain creates is embodied, personal, and does not include information about its creation – and therefore is wholly subjective and unique to each being. How this is done, the mechanism, is available to objective investigation. The subjective cannot see the objective and objective cannot see the subjective. There is a gap and it cannot be removed but neurobiological naturalism can ‘bridge’ it. This conclusion was not new to me as I have always been suspicious of whether the ‘hard question’ was really a question at all.